Americans need safeguards against snooping by intelligence agencies that are tracking terrorists.

In the aftermath of the 9/11 attacks, the Bush administration monitored the international phone calls and emails of hundreds, perhaps thousands, of people within the U.S. without a court order. Seven years after the New York Times broke that story, it is apparent that privacy safeguards legislated in response are inadequate — a deficiency Congress needs to rectify.

The House recently voted to extend for another five years amendments to the Foreign Intelligence Surveillance Act adopted in 2008. The amendments allow U.S. intelligence agencies, with minimal court supervision, to collect vast amounts of electronic communications from sources reasonably believed to be abroad, even if a U.S. resident is at the other end of the conversation. Sen. Ron Wyden (D-Ore.) has placed a hold on similar action in the Senate in the hopes of amending the legislation.

Meanwhile, a group of lawyers, journalists, activists and academics who communicate confidentially with foreigners living abroad has filed suit claiming that the 2008 FISA amendments have made it difficult for them to exercise their constitutional rights and execute their professional obligations. On Monday, the Supreme Court will hear arguments on whether the plaintiffs, represented by the ACLU, have legal standing to bring suit. Given the importance of the constitutional questions involved, the justices should affirm that they do.

But the important actor in protecting the privacy of Americans is Congress. The 2008 amendments do contain some protections for Americans' privacy. For example, the government may not use its authority to gather information abroad to "target" someone known to be in the United States. The law also contains "minimization" procedures placing restrictions on the retention and dissemination of information about U.S. citizens and residents.

But critics say that the prohibition on the targeting of Americans is no guarantee that the government isn't engaging in what the ACLU calls "dragnet surveillance" of Americans' international emails and phone calls. Given that intelligence agencies are trawling for broad categories of information — perhaps as broad as "communications originating in or terminating in Yemen" — it's inevitable that some of those communications will involve people in the U.S.

How many? The office of the director of national intelligence said last year that it is not "reasonably possible" to determine the number of people in the U.S. whose communications may have been "reviewed."

It's generally assumed that most of the collection involves not real-time eavesdropping on phone conversations or instant messages but the downloading of large amounts of information, which is later analyzed. In one scenario, communications from a person in the U.S. would be accessed as part of the scrutiny of a variety of messages sent or received by a foreign target. But some worry that analysts also may use the names of U.S. citizens and residents in their searches of acquired communications. The office of the director of national intelligence insists that the government does not engage in "back door" searches of Americans, but also acknowledges that government operatives have "sometimes circumvented the spirit of the law."

In voting to reauthorize the FISA amendments, the Senate Intelligence Committee concluded that the law "has been implemented with attention to protecting the privacy and civil liberties of U.S. persons." Americans would be more receptive to such assurances if Congress were to adopt two amendments proposed by Wyden and Sen. Mark Udall (D-Colo.).

One would prohibit, in the absence of a court order, "the intentional acquisition of the contents of communications of a particular United States person or the searching of the contents of communications … in an effort to find communications of a particular United States person." (There are exceptions for emergencies in which such information might be necessary to save lives.) The other would require the Justice Department and intelligence agencies to inform Congress of how many people in the U.S. have had their communications either "acquired" or "reviewed."

Congress must strike a new and better balance between national security and the privacy rights of Americans.